The present invention relates to a device and method for measuring and communicating parameters of a brain, tissue or other organs, especially the intracranial pressure or temperature or both in a brain.
A typical adult has a total of about 120-150 cc of (cerebrospinal fluid) CSF with about 25 cc in the ventricles in the brain. A typical adult also produces about 500 cc/day of CSF, all of which is reabsorbed into the blood stream on a continuous basis.
Different conditions can cause the CSF pressure to vary, often in an increasing and dangerous manner. For example, hydrocephalus is a condition of excessive accumulation of CSF in the ventricles or brain cavities. Hydrocephalus can result from congenital conditions interfering with normal CSF circulation or as the result of a problem with CSF re-absorption.
Excessive accumulation of CSF due to hydrocephalus causes increased pressure upon the brain. Whatever the cause, over time, this increased CSF pressure causes damage to the brain tissue. It has been found that shunting the excess CSF to another area of the body is therapeutically beneficial and generally allows the patient to lead a full and active life.
To treat the condition of hydrocephalus, a shunt is used as a conduit to transport CSF from one location in the body to another, for example to the peritoneal cavity or atrium of the heart. A typical shunt for transporting CSF from the ventricle to another part of the body is comprised of a ventricular catheter, valve and distal catheter. CSF shunts also exist for transporting fluid from the spine to another part of the body such as the peritoneal cavity.
Examples of systems to continuously drain excess CSF from the ventricles of the brain are the Delta(copyright) Shunt and the CSFxe2x80x94Flow Control Shunt Assembly made and sold by Medtronicxe2x80x94PS Medical of Goleta, California and as disclosed in U.S. Pat. No. 4,560,375 entitled xe2x80x9cFlow Control Valvexe2x80x9d, issued Dec. 24, 1985 to Rudolf R. Schulte, Gary P. East, Marga M. Bryant and Alfons Heindl. Such systems use a drainage catheter 2 that is placed in the patient""s ventricle 4 in the brain (FIG. 1). The drainage catheter 2 is connected to a valve 6. A ventricular or atrial catheter 8 is connected to the valve 6. The peritoneal or atrial catheter 8 is placed in the patient""s peritoneum or atrium of the heart, respectively, to drain the excess CSF. All of these systems continuously transport excess CSF from the patient""s ventricle through the drainage catheter 2 to another part of the body. For patients with head trauma, who often have increased intracranial pressure at least over some time period. it is often desirable to continuously drain CSF, usually to an external device, to maintain normal CSF pressure in the brain.
Examples of systems to continuously drain excess CSF to an external device are the Becker System(copyright) and the EDM Drainage System(copyright) made and sold by Medtronicxe2x80x94PS Medical of Goleta, Calif. Another example of a system to continuously drain excess CSF is shown in U.S. Pat. No. 4,731,056 issued to William S. Tremulis on Mar. 15, 1988 and entitled xe2x80x9cExternal Drainage Antisiphon Device.xe2x80x9d A further such system is disclosed in U.S. Pat. No. 5,772,625 issued to John A. Krueger, Kevin M. Jaeger and Helmut W. C. Rosenberg on Jun. 30, 1998 and entitled xe2x80x9cExternal Drainage Shunt.xe2x80x9d
A device for measuring and communicating parameters of a brain, tissue or other organs is disclosed. The invention includes a sensor to sense the parameter of interest and then communicate the sensed parameter to an external device where the parameter may be displayed, processed or cause action to be taken. The present invention allows chronic and stable measurement and communication of physiologic parameters to be made.
In a preferred embodiment, the device measures and communicates parameters of a brain, tissue or other organs. Particularly, a device for measuring and communicating the intracranial pressure, CSF pressure or temperature in a brain, tissue or other organ is disclosed.
The invention includes a sensor to sense pressure, intracranial pressure, CSF pressure or temperature. The sensor is preferably located at the distal end of a probe and is preferably placed in the area of the brain, tissue or other organ where a measurement is desired such as the parenchyma or ventricles of the brain.
In the preferred embodiment, the sensor is part of a passive system that allows pressure or temperature measurements to be made and communicated to an attending practitioner when the passive system receives power from an external source. The part of the passive system that receives power from the external source and communicates pressure measurements is preferably located on or next to the skull of the patient while the sensor is locate near or at the area where a measurement is desired to be made.
The passive system couples to an external device that provides power to the passive system. This power is used to power the sensing operation of the sensor and to upload the sensed information from the passive system to an external device. As a result, when coupled to the external power source, the passive system is able to measure and uplink measured physiological parameters such as pressure and temperature measurements from the sensor to an external device.
In an alternate embodiment, the sensor is part of a system having a long-term energy source and storage system that allows pressure or temperature measurements to be taken periodically or upon demand, stored and then communicated to an attending practitioner as desired. The part of the system that provides power, stores pressure or temperature measurements and communicates the pressure or temperature measurements is preferably located on or next to the sub-clavicular region of the patient.
The long-term energy source may be rechargeable. This power from the long-term energy source is used to power the sensing operation of the sensor, store the pressure or temperature measurements and to upload the sensed pressure or temperature information from the system to an external device.
In an alternate embodiment of the invention, the sensed parameter is used to control a pump or valve in a CSF shunt or drainage system. In this embodiment, a pump or valve is placed between a catheter that is placed in the ventricles of the brain and a shunt used as a conduit to transport CSF from one location in the body to another. The pump operates to pump CSF fluid or the valve opens to allow CSF fluid to drain in response to sensed CSF pressure.
The invention also includes, in one embodiment, a method for measuring and communicating parameters of a brain, tissue or other organs. The method includes the steps of providing a sensor to sense the parameter of interest, implanting the sensor in or near a target in the brain, tissue or other organ where the parameter of interest may be sensed, providing a reaction device where the parameter may be displayed, processed or cause action to be taken, sensing the parameter or interest, communicating the sensed parameter to the reaction device and displaying or processing the parameter or causing action to be taken in response to the parameter. In one embodiment of the method, the parameter of interest is the intracranial pressure, CSF pressure or temperature in a brain, tissue or other organ. Also, in another embodiment of the method, the step of providing a sensor includes providing a sensor such as is described herein. Further, in another embodiment of the invention, the method includes the step of providing a CSF shunt or drainage system having a pump or valve and the step of causing action to be taken in response to the parameter includes the step of controlling the pump or valve.
It is an object of one embodiment of the invention to provide a system and method for measuring a physiological parameter such as pressure, intracranial pressure, CSF pressure or temperature that does not require a continuous source of power such as a battery or power capacitor.
It is another object of one embodiment of the invention to provide a device and method that communicates a sensed physiological parameter such as pressure or temperature measurements to an external device.
In another embodiment of the invention, it is an object of the invention to provide a system and method that stores sensed physiological parameters such as sensed pressure or temperature measurements to be uploaded to an external device at a later time.
In a further alternate embodiment of the invention, it is an object of the invention to provide a system and method that actively responds to a sensed physiological parameter to take an action. Specifically, in an alternate embodiment of the invention, it is an object of the invention to provide a CSF shunt or drainage system and method that actively provides information to regulate such shunt or drainage system in response to CSF pressure measurements.
In another alternate embodiment of the invention, it is an object of the invention to provide a sensor of physiological parameters, particularly brain parameters, that requires the tissue of interest to be opened only once to implant the sensor and is thereafter closed and allowed to heal while the implanted sensor provides long-term monitoring of the parameter of interest.
It is an object of the invention in another embodiment of the invention to provide an implantable device that provides information about a body parameter of interest which does not depend on a battery to operate and therefore does not depend on the battery life to remain in operation.
These and other objects of the invention will be clear from the description of the invention contained herein and more particularly with reference to the Figures. Throughout the description, like elements are referred to by like reference numbers. Further, it is clear that to changes to the description contained herein may occur to those skilled in the art and still fall within the scope of the invention. Further, it is clear that the methods of the invention may be practiced with the system or devices shown or may be practiced with other systems and devices as will be clear to those skilled in the art. Therefore, it is not intended that the practice of the methods be limited to such practice only with the specific systems and devices shown.